The present invention relates to a high temperature oil containment boom which allows for the in-situ burning of spilled or leaked oil during offshore oil spill cleanup operations. In-situ burning represents one of the most effective means of eliminating large quantities of spilled oil. If conducted properly, with due consideration for the temporary reduction of air quality and the potential for exposure to fire, the in-situ burning of an oil spill can result in the least overall impact to the environment.
The remoteness of the sites of many oil production and transportation activities such as in Alaska, combined with the nature of the environment, provides ideal conditions for oil spill cleanup through in-situ burning. When considered in comparison to mechanical cleanup, chemical dispersants, and natural elimination processes, burning often provides an important option when some of the other techniques alone are impractical.
Research has revealed that oil can be ignited and combustion sustained when the oil layer on water is at least 1 to 2 mm thick. As thicknesses increase beyond this minimum value, there is less tendency for heat loss to the underlying water and, therefore, the chances are greater for efficient combustion. Thick oil layers have been consistently burned with efficiencies in excess of 95%, even under arctic conditions. To achieve such success through burning, it is important to concentrate any spilled oil as quickly as possible and to contain the burning oil so that winds and/or currents can help thicken the oil slick. During the burning process, temperatures in the order of 1100.degree. C. are common.
Conventional oil containment booms are elongated cylinders having a generally circular cross-section. These booms float in water with approximately one-third of the boom submerged below the surface of the water forming a floating barrier to the spilled oil. The booms are typically stored in a roll on the deck of a ship and deployed downwind of a spill where it floats on the surface of the water and temporarily contains the spill.
Two fireproof oil containment booms for in-situ burning of oil spills were exhibited at the 1985 Oil Spill Conference held at Los Angeles, Calif., Feb. 25 to 27, 1985.
According to its brochure, the TTI Geotechnical Resources Ltd. Fireproof Oilspill Containment Boom consists of alternate rigid flotation units 1.668 m long, 1.78 m high weighing 108.8 kg and flexible (accordian folded) panels 0.906 m long, 1.70 m high weighing 102 kg connected together by connectors 0.07 m long, 1.67 m high weighing 10 kg. The boom is of stainless steel construction and the maximum exposure temperature is stated to be 980.degree. C.
The available literature for the Globe International Inc. Pyroboom fireproof oil spill barrier states that it utilizes a unique blend of refractory and metallic materials in a woven fabric coated with a high temperature polymer coating (silicone rubber). Flotation is provided by a series of stainless steel hemispheres containing a high temperature resistant, closed cellular material. Two such hemispheres with the woven fabric enclosed between them are bolted together to form spheres 16 3/16 inches (41 cm) in diameter spaced 34 inches (86 cm) apart at their centerlines along the length of the woven fabric. The boom has an overall height of 30 inches (76 cm) with a draft of 20 inches (51 cm) and a freeboard of 10 inches (25 cm), and weighs 8 to 10 pounds per lineal foot (11.9 to 14.5 kg/m). The operating temperature range of the boom is stated to be -55.degree. F. to +2400.degree. F. (-48.degree. C. to 1315.degree. C.).
A fire resistant oil containment boom system designated as the SeaCurtain ReelPak FireGard Oil-Fire Containment Boom System is described in a brochure issued by Kepner Plastics Fabricators, Inc. That boom system appears to comprise compartmented circular sections containing a continuous stainless steel coil wire covered with a double walled foam-containing refractory fabric with an additional portion extending downwardly from the circular section, the bottom edge of the downwardly extending section having a chain ballast member attached thereto. The boom is stored on a reel from which it is deployed. The boom is stated to have an operating temperature range from -40.degree. F. to over 2000.degree. F. (-40.degree. C. to 1093.degree. C.) and, depending on model, weighs 2.2 lbs. to 4.2 lbs. per lineal foot (3.3 to 6.3 kg/m).
U.S. Pat. No. 4,537,528 is directed to a fireproof boom for containing a flammable pollutant on a water surface, the boom comprising a flotation member of foamed polypropylene and at least two layers of heat-resistant, water-sorbent material surrounding the flotation member and extending into the water in the form of a depending skirt. The skirt functions to draw water up into the layers of heat-resistant material forming steam in the presence of flaming pollutant thereby allowing only the outer layer of heat-resistant material to become slightly singed. It is understood that a bottom-tensioned, cylindrical-flotation fire containment boom is manufactured by Fire Control Inc. utilizing the teachings of said patent. The boom consists of multiple layers of fire-resistant, wicking fabric positioned over steel canisters for flotation. An additional sacrifical layer and a coarse wire-mesh barrier are used externally for abrasion resistance. The boom weighs 7 lbs. per lineal foot (10.5 kg/m).
An oil boom system utilizes a multilayered, fire-resistant blanket, provided by Minnesota Mining and Manufacturing Company (3M Company), the assignee of the present invention, for use as an add-on high temperature protective blanket to convert most conventional types of boom for the containment of burning oil. The blanket is placed about the periphery of the boom and is held in position by any number of fastening systems.